Here are some resources related to LINQ or Language Integrated Query.
Books
Professional LINQ (Programmer to Programmer)
- This is a pretty good book. I won it in as a door prize at my local .NET user group. It quickly covers LINQ, LINQ to Objects, LINQ to XML and LINQ to SQL providing broad overview without getting bogged down in too many details. A good first book on LINQ.
Microsoft has a couple of books including some free chapters that you can find on their supporting web site.
Scott Gu's Weblog Series on LINQ
Scott also has some video's/webcasts
Design
There's been some noise good and bad about whether or not LINQ to SQL supports good design paradigm's such as n-tier design. I'm trying to round up some links related to this:
N-Tier and Remote Applications with LINQ to SQL on MSDN. Drill down for related articles.
Enterprise Application Architecture with LINQ to SQL By Rohit Gadagkar on code project
Unit Testing
Like the design issues there's lots of discuss around LINQ testability, expecially around support for Test Drive Design.
Awkward Testability for Linq for SQL. See the reponse from Scott Gu point out this resource by Ian Cooper